Tranny Rebuild...

[Mikelly]

So today I got the call from my indy and he gave me the price <Choke choke> of rebuilding this tranny with steel gears in 3-6, along with new syncros, and a new mainshaft with replaceable 1st gear, along with the GT2 clutch slave conversion, and tapping the trans case for the coolers, and the bearings/seals, misc. parts... If I also replace the existing clutch disc with Fibretuff coating, that'll kick it up a tad bit more... We're looking at somewhere north of $8K minimum for everything mentioned, plus the additional cost of the heat exchanger, pump, Tstat and lines. So there you have it. Robert's calling his sources tomorrow to see what he can get, and how long until he can get them. I'm up against a bit of a clock, as I have an evaluation for potential invite to PCA instructor's program coming up in September, and I need a car ASAP... Might be buying a specmiata to get thru the next couple months just to get into this instructor's program. Crazy crazy... Mike

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[D33PBLU3]

Yep, these trannies are pricey, I didn't do the GT2 slave conversion, at least not yet. Fortunately the stock tranny has all the bosses for tapping, its basically the same case for the GT2/3 so its fairly easy to take advantage of all the Porsche Motorsport stuff.

Speaking of Porsche motorsport, they and most vendors have the heat exchangers, lines, synchros and most of the gears, not sure about the main shaft, this was the wait with my setup. Most of the parts that the race teams use are hard to find especially during the race season. I am guessing allot of parts, such as main shafts and certain gears are hoarded, but then become availlable in the off season.

[Mikelly]

So our gameplan is now to drop the car off on September 15th and have the indy check and see what's going on in the gearbox.

Here are the evaluation factors for my setup:

What I'm happy with:
1st gear is fine, I have no issues with it.

2nd gear could be a little taller, but I "could" live with it.

3rd gear, I'd like taller, and stronger, since it takes a beating.

4th gear I'd like a "little" taller, but could be OK with it. Same for the strenght comment above.

5th gear is fine, although a little taller would be good, as my power drops me at a funky place on the back straight at VIR where I'd like to shift, but gettnig me into 6th takes me a little to far. I'd like a taller fifth to eliminate a 5/6 shift there.

6th gear is ok.

I don't want to increase the NOISE factor on this car. It has gained "volume" with the new stiffer trans mount, a little more buzz, but not bad. I'm "hearing" that the steel syncros are pretty loud... not 100% sure. The real reason I'm more concerned about this is if I decide to sell the car to someone who wants it ONLY to drive on the street.

I WILL be doing the GT2 conversion on the clutch hydraulics and I WILL be having the cases tapped for plumbing the heat exchanger plumbing from MOCAL.

Beyond that, I'm in "wait and see" mode, until we crack it open. I'm probably going to keep a stock mainshaft, as 1st simply isn't an issue for me. Once I get the car out of the pits, I'm never back in first gear. It's simply not an issue for me. Driving it on the street, with the torque I build down low, I'm not in it much once the car is rolling... So...

More later...
Mike

[Kato]

Subscribed! Thanks for keeping us in the know! Learning...

[D33PBLU3]

Hey Mike,

I have the steel synchros and don't think there is any sound difference, to think about it not much sound difference in the tranny at all.

Before I opened the tranny and dove into this project, I was ok with the ratios as well, I thought first was a little too short but...I wasnt going to go out of my way to do anything about it. However, since I was already in the tranny and was redoing things, I figured this was the time if I was going to do anything. The longer 1st is nice, actually usable.

3rd definitely needs to be stronger, its the gear that takes a beating, although mine looked good. Its good you are looking at the shift points, pm me your email and I will drop you a spreadhseet with some calculations, including tire diameter and R&P and final gear, its nice to figure out where you want your shift points compared to rpm and boost.

//Anders

Originally Posted by Mikelly

So our gameplan is now to drop the car off on September 15th and have the indy check and see what's going on in the gearbox.

Here are the evaluation factors for my setup:

What I'm happy with:
1st gear is fine, I have no issues with it.

2nd gear could be a little taller, but I "could" live with it.

3rd gear, I'd like taller, and stronger, since it takes a beating.

4th gear I'd like a "little" taller, but could be OK with it. Same for the strenght comment above.

5th gear is fine, although a little taller would be good, as my power drops me at a funky place on the back straight at VIR where I'd like to shift, but gettnig me into 6th takes me a little to far. I'd like a taller fifth to eliminate a 5/6 shift there.

6th gear is ok.

I don't want to increase the NOISE factor on this car. It has gained "volume" with the new stiffer trans mount, a little more buzz, but not bad. I'm "hearing" that the steel syncros are pretty loud... not 100% sure. The real reason I'm more concerned about this is if I decide to sell the car to someone who wants it ONLY to drive on the street.

I WILL be doing the GT2 conversion on the clutch hydraulics and I WILL be having the cases tapped for plumbing the heat exchanger plumbing from MOCAL.

Beyond that, I'm in "wait and see" mode, until we crack it open. I'm probably going to keep a stock mainshaft, as 1st simply isn't an issue for me. Once I get the car out of the pits, I'm never back in first gear. It's simply not an issue for me. Driving it on the street, with the torque I build down low, I'm not in it much once the car is rolling... So...

More later...
Mike

[heavychevy]

Without changing the final drive:

I'd like a taller third, but ONLY with a taller 2nd as 2nd for me is pretty much useless on the track as it is. 3rd being taller would eliminate a lot of short shifts for me as well. In that case I'd make 2nd - 4th stronger as well.

I'm also interested in Al's gearbox cooler as it seems to work really well and wouldn't mind some steel syncros.

[tom kerr]

mike leave the main shaft and first gear ALONE!! that is were the cost is and not worth it.
the steel syncros are cheap, rebuild the tranny with the steel syncros (remember they need to warm up not like the brass ones) put a cooler on it and be done
that should be under 4k!!

[heavychevy]

Where did you get your gears and synchros from Tom?

[Prche951]

Originally Posted by tom kerr

mike leave the main shaft and first gear ALONE!! that is were the cost is and not worth it.
the steel syncros are cheap, rebuild the tranny with the steel syncros (remember they need to warm up not like the brass ones) put a cooler on it and be done
that should be under 4k!!

not sure I agree with this logic. How many times have you rebuilt your trans? Once and it is still alive, or 3-4 times? if the latter, I would say that your cost is probably higher than what DEEPBLUE has done to build his trans the right way. Pay now or pay later, but you will pay.

[heavychevy]

Tom has the most highly stressed gearbox in a 996 TT that I know of so there is no assurance that even what D33PBLU3 has done will actually hold up to what Tom puts it through.

I think replacing bits and pieces is inevitable in racing, pro teams tear down and rebuild gearboxes several times a season. Racing is a different animal, and unfortunately all of the Porsche stuff is built for NA, low torque vehicles. Not big torque monster turbos. If you race the car, or track as much as Tom always has, you will rebuild occasionally, or at least fix bits and pieces.

[Prche951]

Originally Posted by heavychevy

Tom has the most highly stressed gearbox in a 996 TT that I know of so there is no assurance that even what D33PBLU3 has done will actually hold up to what Tom puts it through.

I think replacing bits and pieces is inevitable in racing, pro teams tear down and rebuild gearboxes several times a season. Racing is a different animal, and unfortunately all of the Porsche stuff is built for NA, low torque vehicles. Not big torque monster turbos. If you race the car, or track as much as Tom always has, you will rebuild occasionally, or at least fix bits and pieces.

I see your point about Toms tranny. But for most of the rest of us, doing it right the first time is better than having to go back many times. Labor is a killer in these cars.

[WOODTSTER]

^^^ So true Dez,

Cup Car trans get rebuilt after so many hours and everytime
they change the lube in them metal shavings come out with
the lube.

If you were to use it like Tom does, expect periodic rebuilds.

[jcb-memphis]

For normal street I have chosen just because that is what I want to change fluids every 30k. The local speed shop has done testing on gt3's with 4-5 DE's season and feels that is reasonable.

If I track, I plan to do it every 8 track days. Mix...7500 miles is 2 track days. Simple, linear. Just my plan.

They have had the fluid analyzed...I have not, I just had my 2nd gear pop-out fixed and ran out of money to do the cooler.

A tranny cooler is planned.....

Jeff

[D33PBLU3]

You're absolutely right, a good chunk of the cost was labor, even the "friend" discount adds up. To be fair, part of this was the "initial" build, initial machine work, initial parts, initial LSD, etc... The cost of repair will be much lower, but even in the case of Mikes car, its $4-5k car for minimal work, thats still quite a bit.

Not sure what all Tom has done, what his race budget is or if he is repairing the same things repeatedly, he definitely has quite a bit of experience which should definitely be considered, however we all have different scenarios. I think an pound of prevention goes a very long way here. Steel synchros, scheduled fluid changes, tranny cooler, a stronger 3rd gear etc...might as well pay up front and lower the over all Cost of Ownership. This is why I "went big", I do anticipate eventual repairs, but I feel I have mitigated allot of that risk.

Originally Posted by Prche951

I see your point about Toms tranny. But for most of the rest of us, doing it right the first time is better than having to go back many times. Labor is a killer in these cars.

[heavychevy]

Originally Posted by Prche951

I see your point about Toms tranny. But for most of the rest of us, doing it right the first time is better than having to go back many times. Labor is a killer in these cars.

- Lets keep things in perspective here, only a handful of people here are even driving on the track frequently enough or pushing hard enough to even really surpass the threshold of the stock components to much extent. Those that do, are likely running R-tires and will have some bad shifts and missed shifts that damage the synchros and weaken 3rd gear since it's the most used gear on pretty much any track. So encouraging anyone who pops the gearbox out because third gear feels weak or the synchros are going to make 10k cup car trannies is a bit overzealous. Tom has years of experience driving on what he's rebuilt, D33PBLUE3 hasn't even tested what he's built yet, nor do we know what he's actually going to do with it. It could last him forever if he's just doing a few DE's a year, but most people can last almost that long on a stock tranny. There is no arguing that Tom hasn't had his gearbox open more than pretty much all of us and has seen what breaks and what doesn't, that's about as valuable an opinion as you can get.

-For the gearbox, you certainly don't need 1st gear (unless it's a drag car), in which case the whole scenario changes, and in many cases, unless 2nd is used at all on track which is very rare considering how short it is, you don't need that either. Why replace the mainshaft? If I replace anything there will be a specific purpose behind it, not any just because situations for me.

- On the track, unless your ratios are changed, you are nearly exclusively 3rd and 4th and on faster tracks 5th, maybe 6th. Get your desired gear ratios, the the wider stronger versions, do the synchros put some cooling on it and be done with it.

- The fact is a few bad shifts can break anything you put in the gearbox, so it'll pay more for all of us to have coaching on proper shifting techniques.